What is the reason for the failure to shift between high and low gears?
2 Answers
The shifting valve is damaged. Below is an introduction to the shifting valve: 1. Introduction: The shifting valve (forced valve) is an air-operated switch valve installed at the hot end of a switching heat exchanger (or regenerator), which uses the principle of a linkage structure to achieve the opening and closing of the valve plate. 2. Equipment introduction: The switching of the shifting valve is controlled by signal compressed air from the solenoid valve. Depending on their role in the process, there are air and dirty nitrogen shifting valves, pure nitrogen suppression valves, and dirty nitrogen three-way valves, among others. Structurally, they can be divided into vertical and horizontal types. Vertical shifting valves can be further divided into air-to-open and air-to-close types. Air-to-open means that when the signal compressed air is cut off, the valve disc can automatically open under its own weight. The opposite is air-to-close. The choice between air-to-open and air-to-close is determined by the safety requirements of the device. Nitrogen shifting valves use the air-to-open type, while air shifting valves use the air-to-close type.
Last time my car couldn't shift between high and low gears, I suspected it was due to old or insufficient transmission fluid - when the oil gets too thin, the gears can't grip properly. It could also be clutch wear, where power isn't transferred during shifting, causing the transmission to get stuck in one gear. For automatic transmissions, a faulty temperature sensor might mislead the control module and prevent gear changes. I recommend first checking the dipstick - if the fluid level is low, top it up with fresh oil but don't randomly switch brands. If the fluid looks clean but problems persist, it's likely an internal valve body or synchronizer issue requiring professional disassembly and repair. Never force a gear shift to avoid gear damage and more expensive repairs. For safety, visit a repair shop ASAP - they have diagnostic tools to read trouble codes, saving time and hassle. Regular pre-drive fluid checks can prevent most transmission issues.
